Active avoidance from a crude oil soluble fraction by an Andean paramo copepod

Araújo, Cristiano V. M.; Moreira-Santos, Matilde; Sousa, José P.; Ochoa-Herrera, Valeria; Encalada, Andrea C.; Ribeiro, Rui

Active avoidance from a crude oil soluble fraction by an Andean paramo copepod

2014

Several oil spills due to ruptures in the pipeline oil systems have occurred at the Andean paramo. A sample of this crude oil was mixed with water from a nearby Andean lagoon and the toxicity of the soluble fraction was assessed through lethal and avoidance assays with a locally occurring copepod (Boeckella occidentalis intermedia). The integration of mortality and avoidance aimed at predicting the immediate decline of copepod populations facing an oil leakage. The 24-h median lethal PAH concentration was 42.7 (26.4–91.6) µg L⁻¹. In the 12-h avoidance assay, 30 % avoidance was recorded at the highest PAH concentration (19.4 µg L⁻¹). The mortality at this PAH concentration would be of 25 % and, thus, the population immediate decline would be of 55 %. The inclusion of non-forced exposure testing with the quantification of the avoidance response in environmental risk assessments is, therefore, supported due to underestimation of the lethal assays.

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